This invention relates generally to nuclear reactors and more particularly, to core spray sparger assemblies within such reactors.
A reactor pressure vessel (RPV) of a boiling water reactor (BWR) typically has a generally cylindrical shape and is closed at both ends, e.g., by a bottom head and a removable top head. A shroud surrounds the core and is supported by a shroud support structure.
Boiling water reactors have numerous piping systems, and such piping systems are utilized, for example, to transport water throughout the RPV. For example, some BWR""s include an emergency core cooling system, configured to spray coolant over each fuel assembly in the event of a loss of coolant accident. Core spray piping is used to supply water from outside the RPV to core spray spargers inside the RPV. The core spray spargers supply coolant to the fuel assemblies. In some situations, the core spray sparger can supply coolant containing boron to the fuel assemblies to suppress fission.
Core spray spargers are generally classified as ring spargers or grid spargers. Both types require extensive, laborious efforts to ensure coolant is supplied to the fuel assemblies. Ring spargers generally include peripheral rings with adjustable spray nozzle units. Ring spargers nozzle units require time consuming field alignment of each nozzle unit. Such field alignment is particularly difficult if nozzle units must be replaced or temporally removed after reactor operation due to the radiation field. Grid spargers generally include a complex grid that can cause an undesirable pressure drop in the normal coolant flowpath and complicates inspection of RPV areas above the fuel assemblies. Further, grid spargers themselves require extensive inspection due to the number of components, welds, and joints presented by their construction.
In one aspect, a core spray sparger assembly is provided for a nuclear reactor that includes fuel assemblies, a top guide, coolant supply pipes and a shroud head. The core spray sparger assembly includes at least one coolant manifold, at least one coolant coupling in fluid communication with the coolant manifold, and at least one mounting device configured to couple the coolant manifold to the nuclear reactor. The core spray sparger assembly further includes a plurality of fluid conductors in a parallel array positioned above the fuel assemblies, the fluid conductors in fluid communication with the coolant manifold, and a plurality of nozzles in fluid communication with the fluid conductors.
In another aspect, a core spray sparger assembly is provided for a nuclear reactor that includes a top guide and fuel assemblies. The core spray sparger assembly includes a pair of independent, coaxial, substantially circular, coolant manifolds, joined by a plurality of resilient couplings. The core spray sparger assembly also includes at least one coolant coupling in fluid communication with each coolant manifold and at least one boron coolant coupling in fluid communication with each coolant manifold. The core spray sparger assembly further includes at least one mounting device, two parallel arrays, at least one stabilizing member, and a plurality of nozzles. The mounting device couples the coolant manifolds to the nuclear reactor. Two parallel arrays of fluidically independent, parallel fluid conductors are configured to be positioned above the reactor top guide, each array in fluid communication with one of the coolant manifolds. The stabilizing member is coupled to one of the coolant manifolds and at least one of the fluid conductors. The nozzles are in fluid communication with the fluid conductors.
In another aspect, a nuclear reactor is provided that includes a plurality of fuel assemblies, at least one coolant supply pipe, a top core guide above side fuel assemblies, a shroud head above the top core guide, and a core spray sparger assembly. The core spray sparger assembly includes at least one coolant manifold, at least one coolant coupling in fluid communication with the coolant manifold, at least one mounting device coupling the coolant manifold to the nuclear reactor, a plurality of fluid conductors in a parallel array, positioned above the top guide, in fluid communication with the coolant manifold, and a plurality of nozzles in fluid communication with the fluid conductors, configured to supply coolant to the fuel assemblies.